CVE-2024-56587

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> leds: class: Protect brightness_show() with led_cdev-&gt;led_access mutex<br /> <br /> There is NULL pointer issue observed if from Process A where hid device<br /> being added which results in adding a led_cdev addition and later a<br /> another call to access of led_cdev attribute from Process B can result<br /> in NULL pointer issue.<br /> <br /> Use mutex led_cdev-&gt;led_access to protect access to led-&gt;cdev and its<br /> attribute inside brightness_show() and max_brightness_show() and also<br /> update the comment for mutex that it should be used to protect the led<br /> class device fields.<br /> <br /> Process A Process B<br /> <br /> kthread+0x114<br /> worker_thread+0x244<br /> process_scheduled_works+0x248<br /> uhid_device_add_worker+0x24<br /> hid_add_device+0x120<br /> device_add+0x268<br /> bus_probe_device+0x94<br /> device_initial_probe+0x14<br /> __device_attach+0xfc<br /> bus_for_each_drv+0x10c<br /> __device_attach_driver+0x14c<br /> driver_probe_device+0x3c<br /> __driver_probe_device+0xa0<br /> really_probe+0x190<br /> hid_device_probe+0x130<br /> ps_probe+0x990<br /> ps_led_register+0x94<br /> devm_led_classdev_register_ext+0x58<br /> led_classdev_register_ext+0x1f8<br /> device_create_with_groups+0x48<br /> device_create_groups_vargs+0xc8<br /> device_add+0x244<br /> kobject_uevent+0x14<br /> kobject_uevent_env[jt]+0x224<br /> mutex_unlock[jt]+0xc4<br /> __mutex_unlock_slowpath+0xd4<br /> wake_up_q+0x70<br /> try_to_wake_up[jt]+0x48c<br /> preempt_schedule_common+0x28<br /> __schedule+0x628<br /> __switch_to+0x174<br /> el0t_64_sync+0x1a8/0x1ac<br /> el0t_64_sync_handler+0x68/0xbc<br /> el0_svc+0x38/0x68<br /> do_el0_svc+0x1c/0x28<br /> el0_svc_common+0x80/0xe0<br /> invoke_syscall+0x58/0x114<br /> __arm64_sys_read+0x1c/0x2c<br /> ksys_read+0x78/0xe8<br /> vfs_read+0x1e0/0x2c8<br /> kernfs_fop_read_iter+0x68/0x1b4<br /> seq_read_iter+0x158/0x4ec<br /> kernfs_seq_show+0x44/0x54<br /> sysfs_kf_seq_show+0xb4/0x130<br /> dev_attr_show+0x38/0x74<br /> brightness_show+0x20/0x4c<br /> dualshock4_led_get_brightness+0xc/0x74<br /> <br /> [ 3313.874295][ T4013] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000060<br /> [ 3313.874301][ T4013] Mem abort info:<br /> [ 3313.874303][ T4013] ESR = 0x0000000096000006<br /> [ 3313.874305][ T4013] EC = 0x25: DABT (current EL), IL = 32 bits<br /> [ 3313.874307][ T4013] SET = 0, FnV = 0<br /> [ 3313.874309][ T4013] EA = 0, S1PTW = 0<br /> [ 3313.874311][ T4013] FSC = 0x06: level 2 translation fault<br /> [ 3313.874313][ T4013] Data abort info:<br /> [ 3313.874314][ T4013] ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000<br /> [ 3313.874316][ T4013] CM = 0, WnR = 0, TnD = 0, TagAccess = 0<br /> [ 3313.874318][ T4013] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0<br /> [ 3313.874320][ T4013] user pgtable: 4k pages, 39-bit VAs, pgdp=00000008f2b0a000<br /> ..<br /> <br /> [ 3313.874332][ T4013] Dumping ftrace buffer:<br /> [ 3313.874334][ T4013] (ftrace buffer empty)<br /> ..<br /> ..<br /> [ dd3313.874639][ T4013] CPU: 6 PID: 4013 Comm: InputReader<br /> [ 3313.874648][ T4013] pc : dualshock4_led_get_brightness+0xc/0x74<br /> [ 3313.874653][ T4013] lr : led_update_brightness+0x38/0x60<br /> [ 3313.874656][ T4013] sp : ffffffc0b910bbd0<br /> ..<br /> ..<br /> [ 3313.874685][ T4013] Call trace:<br /> [ 3313.874687][ T4013] dualshock4_led_get_brightness+0xc/0x74<br /> [ 3313.874690][ T4013] brightness_show+0x20/0x4c<br /> [ 3313.874692][ T4013] dev_attr_show+0x38/0x74<br /> [ 3313.874696][ T4013] sysfs_kf_seq_show+0xb4/0x130<br /> [ 3313.874700][ T4013] kernfs_seq_show+0x44/0x54<br /> [ 3313.874703][ T4013] seq_read_iter+0x158/0x4ec<br /> [ 3313.874705][ T4013] kernfs_fop_read_iter+0x68/0x1b4<br /> [ 3313.874708][ T4013] vfs_read+0x1e0/0x2c8<br /> [ 3313.874711][ T4013] ksys_read+0x78/0xe8<br /> [ 3313.874714][ T4013] __arm64_sys_read+0x1c/0x2c<br /> [ 3313.874718][ T4013] invoke_syscall+0x58/0x114<br /> [ 3313.874721][ T4013] el0_svc_common+0x80/0xe0<br /> [ 3313.874724][ T4013] do_el0_svc+0x1c/0x28<br /> [ 3313.874727][ T4013] el0_svc+0x38/0x68<br /> [ 3313.874730][ T4013] el0t_64_sync_handler+0x68/0xbc<br /> [ 3313.874732][ T4013] el0t_64_sync+0x1a8/0x1ac